The present invention is directed generally to printing presses and more particularly to a plate cylinder of a printing press, to a register pin adjustment device and to a method for adjusting a register pin.
U.S. Pat. No. 6,382,103 discloses a lateral registration device for printing plates in a plate cylinder, using axially shiftable insertion strips. The strips have register pins which engage recesses in beveled end of the flexible printing plates. Each register pin is fixedly connected to an insertion strip or made of one piece with it.
U.S. Pat. No. 5,419,248 discloses a device for aligning printing plates on a plate cylinder. A plurality of adjustment elements spaced apart from one another are located in a bore. The adjustable elements have moveable register pins thereon. Each adjustment element is fixed to the bore by turning a spreading screw, which spread wings of the adjustment element to wedge the adjustment element in the bore to provide a course adjustment. For fine adjustment, a threaded screw is rotated to move the register pin relative to the adjustment element. An actuating rod for tensioning elements does not move the adjustable elements.
U.S. Pat. Nos. 4,748,911 and 5,379,694 disclose other later register adjustment devices.
An object of the present invention is to reduce the manufacturing tolerances necessary for a register device. An alternate or additional object of the present invention is to provide a register device which is easy to install.
The present invention provides a register device for insertion into a channel of a printing unit cylinder. The device includes a rod defining an axial direction and a pin support movable in the axial direction by the rod, the rod being movable with respect to the pin support in a direction perpendicular to the axial direction. A register pin is attached to the pin support.
The pin support generally slides in axially in the channel with little or no clearance. By permitting the rod to move in the axial direction with respect to the pin support, the register device is easy to install and manufacturing tolerances, including those for the channel, may be reduced.
The rod may be movable in the axial direction with respect to the pin support, for example, by providing a hole in the pin support, with the pin support receiving the rod with a clearance in the hole.
The rod provides for fine adjustment of the register pin in the axial direction.
It may also be desirable to provide a coarse adjustment, for example for different web widths. The pin support thus may be adjustable with respect to the rod when removed from the machine, for example by placing holding bolts in different axial locations along the rod. Alternately, rods of different length could be used to provide this course adjustment.
The register device may include a second rod, a second pin support and a second register pin, or as many register pins as necessary.
When the register device is installed, the rod may move the register pins axially, and the pin support is generally axially fixed with respect to the rod. However, to aid in permitting the movement of the pin support in the direction perpendicular to the axial direction, and the pin support may be attached to the rod so that the pin support can move in the axial direction with respect to the rod by a movement amount, the movement amount being less than 0.1 millimeters. This amount generally will not adversely affect print quality, depending on the type of print job.
The present invention also provides a register device for insertion into a channel of a printing unit cylinder having a rod defining an axial direction, a pin support movable in the axial direction by the rod, a shim replaceably connected to the pin support, and a register pin supported on the shim.
By having a replaceable shim, the thickness of the shim can be adjusted so that the register pin is located at the proper distance from the pin support. This permits the register pin to fit into the slot in the plate cylinder so that the register pin and the pin support slide axially with ease through the channel. Ease of installation can be increased, as can manufacturing tolerances.
The present invention also provides a plate cylinder having a channel for receiving the register devices, as well as a method for adjusting the axial registration of a printing plate using the devices.
The present invention also provides a method for installing a register device in a channel and a slot of a printing unit cylinder comprising the steps of: placing a pin support having a register pin in the channel so that the register pin extends into the slot; determining if the pin support and the register pin slide axially in the channel; and if the pin support and register pin do not slide axially in the channel, placing a shim between the register pin and the pin support.